Author Topic: MAF Conversion: It's Happening, Who Is Interested? (Read 39274 times)

bmwman91 · « **Reply #15 on:** May 16, 2012, 02:51:37 PM »

Haha thanks, Dave. I got a guy on eBay to give me the rough dimensions of one actually!

Here's the MAF:
http://www.ecstuning.com/Search/461L/ES517741/

This particular one was used on all VW 1.8T motors. However, there are 4 or 5 variants of this housing, all with the same sensing element & inner diameter that only differ in the mounting flanges & coupling details. This sensor/housing was used with many car makers, with anything from a 1.8L I4 to some Vw 4.2L V8's making ~360HP stock. It has more than enough flow capacity for any E30 motor, and even a stock M30 as far as I can tell.

colin86325 · « **Reply #16 on:** May 16, 2012, 04:06:41 PM »

I wonder whether the conversion will have an impact on fuel economy? It would seem that the MAF could possibly be more accurate, resulting in better economy.

bmwman91 · « **Reply #17 on:** May 17, 2012, 12:16:27 AM »

Nah, I don't foresee any improvements in fuel economy. The stock VAM was pretty accurate actually. It really isn't a BAD sensor, but they are all old, worn out and very expensive to replace. The O2 sensor can help the Motronic to adapt to a lot of wear & tear on the stock sensors & stuff. The technology is old, but proven. MAFs are nice because they give much faster response and don't have moving parts to wear out, and at this point, the conversion should cost about the same as a rebuilt VAM.

monty23psk · « **Reply #18 on:** May 17, 2012, 10:06:03 AM »

^ this is the point I will get one. With the new house and baby, a s52 swap is way to down the road so I need to keep my m42 running heathly with a few perks...

I do have one question, what if you add a chip to the ECU? Does it hava better impact with the MAF? Anything else need to be done to the MAF?

bmwman91 · « **Reply #19 on:** May 17, 2012, 12:12:38 PM »

You should not need to do anything differently with the MAF conversion, no matter which chip you run. An aftermarket chip wouldn't take any MORE advantage of the MAF though, since chips don't make changes to the actual executable code for the ECU, just the look-up tables for fuel & spark. At this point, the MAF is "faster" than the old ECU in these cars!

Now, if one were to increase their M42's displacement, I think that the MAF would start to confer even more benefits.

bmwman91 · « **Reply #20 on:** May 20, 2012, 12:21:08 AM »

Well, today was a good day. I got enough of the wiring harness assembled to bench-test the first PCB, and it works more or less as expected! The various settings work properly, the outputs are clean & in the proper ranges, both the analog & digital filters appear to be working as designed, serial communication works, firmware updates apply properly and overall the thing looks like it will be good enough for use in a first batch! There is still some testing to be done, and a few little nagging annoyances were found in the user interface that I want to correct, as well as some random misbehavior when the power is turned on & off repeatedly while the USB cable is connected to a PC. So, none of the issues affect normal operation, which is good, but I want to clear them up as best I can anyway.

I'll probably need another week or so to get this one all done & to my liking. Thereafter, I will see about assembling 3 more to send to "beta testers". It will require a little cutting of the factory harness, but the parts that will be supplied will make conversion between this & the stock setup truly plug & play. The only tools someone will need will be some plain old crimpers for butt splices & a heat gun for those splices' insulation (a hair dryer might work too, maybe).

Keep in mind that this doesn't include the MAF sensor. They range from $70 rebuilt to $110 for a new Bosch one, to $220 for an OEM VW one (same as the Bosch one, but pricier for no reason).

BKCowGod · « **Reply #21 on:** May 20, 2012, 02:20:57 AM »

Hey - I'm next door in Sunnyvale and about to be on summer vacation. Lemme know if I can be of any assistance.

lqbanotxano · « **Reply #22 on:** May 20, 2012, 09:43:22 AM »

Would some porting/head work & little hotter intake cam add to the benefits of the MAF conversion?

bmwman91 · « **Reply #23 on:** May 20, 2012, 11:15:42 AM »

Quote from: lqbanotxano;112648

Would some porting/head work & little hotter intake cam add to the benefits of the MAF conversion?

Yup, an M42 that sucks more air than a stock one will get more benefit from the MAF. The stock AFM is well-suited to a stock M42, but once you start pulling more air, it does start adding a bit of restriction.

bmwman91 · « **Reply #24 on:** May 20, 2012, 11:16:39 AM »

Quote from: BKCowGod;112646

Hey - I'm next door in Sunnyvale and about to be on summer vacation. Lemme know if I can be of any assistance.

I'll let you know...my car is out of commission for the next month or so. With that being the case, I'll need a couple of local "test subjects" haha!

bmwman91 · « **Reply #25 on:** May 27, 2012, 02:30:51 AM »

I figured that some of you might like to see some progress pics. Here's the first module. I am still working out a few details on the wiring harness, but this is the general design. One thing I still need to do is track down some potting adhesive to seal up the little plastic box that the converter lives in. The trick is finding some that does not harm electronics or corrode metal since it will sort of be sealed into the box with them!

Anyway...enough babble.

Top side of the motherboard. Voltage regulator, power resistors, poly-fuses & the USB comm chip.

Bottom side of the motherboard. DSP controller, poly-fuse protection on the 5V input from the ECU, DAC, anti-aliasing filters and reconstruction filter.

Parts are industrial grade where needed. I worked out all the power dissipation calcs for worst-case scenarios, and this sucker can operate with the air under the hood at 107�C, minimum.

Here's the wiring harness & its components. The thermistor module is modular so that any car can use this once I determine the NTC parameters for the thermistor in the original AFM. Just about every AFM uses a different one (M42, M20 & M30 are all different...I wonder if M20 guys with M30 AFMs know this...).

I made most parts of this easily disconnectable so that users can easily swap this in & out. The power harness is sort of permanently installed since you need to splice it into a 12V line from the main relay, but the rest is easily removable. You may notice the M42 AFM plug on here...I was given one of those AFM extensions by another member here and I have found a source for the connector housings. The bad news is that there are only 26 of those rubber boots for the plug left in the WORLD!

The plan is to sell this with a pig-tail that is spliced into the stock AFM harness. All you need to do is match wire colors, crimp some butt splices & put on the sheathing that I supply. There will be an extra pig-tail for the stock AFM connector that you have to chop off so that you can easily put it back. I may offer the M42 plug as an option, but it will add $50 to the cost of the kit and add around 4 weeks to the lead time since the parts all have to come from Germany.

2002Harv · « **Reply #26 on:** June 02, 2012, 10:01:35 PM »

I like it.

John

DesktopDave · « **Reply #27 on:** June 03, 2012, 07:56:54 AM »

That is tremendous - the thoroughness of your work is impressive.

The modular setup is a great idea too. I'll bet most buyers will opt to simply cut the stock harness and install your updated parts. OEM is nice for a cherry low-mileage coupe, but a lot of our cars are no longer pristine specimens and don't carry much value...:rolleyes:

bmwman91 · « **Reply #28 on:** June 03, 2012, 12:50:41 PM »

Quote from: DesktopDave;112951

That is tremendous - the thoroughness of your work is impressive.

The modular setup is a great idea too. I'll bet most buyers will opt to simply cut the stock harness and install your updated parts. OEM is nice for a cherry low-mileage coupe, but a lot of our cars are no longer pristine specimens and don't carry much value...:rolleyes:

Ha yeah tell me about it. My car isn't really a pristine show-room sample. The motor that is coming in a couple of weeks needs its own insurance policy lol.

I am going to test this out on my sister's E36 M42 later this week. I expect everything to be fine since my bench-tests show it operating properly. Then I should be able to test it out on my new motor, and then start building some of these! I may see if I can work out some sort of adapter plate to sell with it (for those that want to keep a stock look & chop up their stock air box a little...I passed CA SMOG with a setup like that), although all anyone really needs is some 2.75" OD acrylic tubing from TAP plastics and a cone air filter.

monty23psk · « **Reply #29 on:** October 04, 2012, 11:11:01 AM »

Congrats on getting the new engine going. Were there any plans on this MAF?